[Pw_forum] R: Pw_forum Digest, Vol 82, Issue 16

Tommy neutrinofrancese at gmail.com
Fri May 16 23:23:34 CEST 2014


Thanks a lot to Prof. Matteo Cococcioni and Pang Rui for your tips!

----- Messaggio originale -----
Da: pw_forum-request at pwscf.org
Inviato: 16/05/2014 12:03
A: pw_forum at pwscf.org
Oggetto: Pw_forum Digest, Vol 82, Issue 16

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Today's Topics:

   1. Hubbard coefficients (Tommy)
   2. Re: Hubbard coefficients (Matteo Cococcioni)
   3. drawing  the HOMO and LUMO (Banafshe Noori)
   4. Hubbard U (Tommaso Francese)
   5. Re: Hubbard U (Matteo Cococcioni)
   6. Re: Hubbard U (Pang Rui)


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Message: 1
Date: Thu, 15 May 2014 23:16:48 +0200
From: Tommy <neutrinofrancese at gmail.com>
Subject: [Pw_forum] Hubbard coefficients
To: "pw_forum at pwscf.org" <pw_forum at pwscf.org>
Message-ID: <53752edb.81430f0a.46b0.0c2a at mx.google.com>
Content-Type: text/plain; charset="windows-1252"

Thanks to both Giuseppe Mattioli and Pang Gui for their help!!! 
However, I need to ask one more question about the process for obtaining Hubbard coefficients: I follow the tutorials posted with the links, but a thing wasn't clear to me. After scf simple calculation, I need to "perturb" the system in a range between -0.1 & 0.1 eV. But: do i need to save a file for every perturbation induced to the system?
How can i set to QE to take every previous result and compute the U term?
Be patient, but I'm alone and i trying to do the best for my thesis!!!
Best regards,
Tommaso.
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Message: 2
Date: Fri, 16 May 2014 00:06:39 +0200
From: Matteo Cococcioni <matteo at umn.edu>
Subject: Re: [Pw_forum] Hubbard coefficients
To: PWSCF Forum <pw_forum at pwscf.org>
Message-ID:
	<CAMZASgEDkxq6rpEGcazeVFmy_WO1iXAsPbW589DpaVYaMRgUeg at mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

Hi Tommaso,

for every perturbation the run should restart from the potential (and
wavefunctions) of the uperturbed run. So you need to save the scratch
directory of the latter and copy it to the one used by the perturbed run
before each calculation. This should be evident from the tutorial files.
Also make sure that diago_thr_init (the threshold for the diagonalization
of the Hamiltonian at each step) is set equal to the value it had at the
last iteration of the unperturbed run, so that the diagonalization at the
first iteration of the perturbed run is equally ccurate. Hope this is not
confusing.

best,

Matteo




On Thu, May 15, 2014 at 11:16 PM, Tommy <neutrinofrancese at gmail.com> wrote:

> Thanks to both Giuseppe Mattioli and Pang Gui for their help!!!
> However, I need to ask one more question about the process for obtaining
> Hubbard coefficients: I follow the tutorials posted with the links, but a
> thing wasn't clear to me. After scf simple calculation, I need to "perturb"
> the system in a range between -0.1 & 0.1 eV. But: do i need to save a file
> for every perturbation induced to the system?
> How can i set to QE to take every previous result and compute the U term?
> Be patient, but I'm alone and i trying to do the best for my thesis!!!
> Best regards,
> Tommaso.
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://pwscf.org/mailman/listinfo/pw_forum
>
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Message: 3
Date: Fri, 16 May 2014 07:43:04 +0100 (BST)
From: Banafshe Noori <b_noori88 at yahoo.com>
Subject: [Pw_forum] drawing  the HOMO and LUMO
To: "pw_forum at pwscf.org" <pw_forum at pwscf.org>
Message-ID:
	<1400222584.49542.YahooMailNeo at web171505.mail.ir2.yahoo.com>
Content-Type: text/plain; charset="iso-8859-1"

Dear all,


Hi


How can? draw? the HOMO and LUMO orbital of nanotube? with pwscf package?

please guide me.

thanks.
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Message: 4
Date: Fri, 16 May 2014 10:40:54 +0200
From: Tommaso Francese <neutrinofrancese at gmail.com>
Subject: [Pw_forum] Hubbard U
To: pw_forum at pwscf.org
Message-ID: <D2267729-B244-4A28-B36F-07740EED2067 at gmail.com>
Content-Type: text/plain; charset=windows-1252

Dear all,
 as you suggested, i try to follow your tutorial for the Hubbard U coefficients determination, but i have some practical difficulties. 

Summarizing, i proceded as follow:

step 1)?> i have done a simple SCF with very low coefficients for Hubbard_U1 and Hubbard_U2, enabling the wavefunction separate collection (wf_collect) ;
step 2)?> i have performed some SCF, restarting from the charge file stored previously,  introducing some fluctuation values in Hubbard_alpha (?), is it correct? 

the problem is at this point: do i need to rename every scf-file in which i performed a different perturbation? How can i, in the next step, ?recall? the different perturbation that i performed previously? 

At this point is obvious that i don?t know also how to calculate the response functions and so, obtaining the Hubbard U coefficient.

Can someone help me? 
Thanks a lot,
Tommaso,
Universit? C? Foscari of Venice


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Message: 5
Date: Fri, 16 May 2014 11:08:22 +0200
From: Matteo Cococcioni <matteo at umn.edu>
Subject: Re: [Pw_forum] Hubbard U
To: PWSCF Forum <pw_forum at pwscf.org>
Message-ID:
	<CAMZASgEWM9Gn0bWrgyMc5ZOb3RvSJK2EtDsfD3ePPBCA4p2nAQ at mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

Dear Tommaso,

see below.

On Fri, May 16, 2014 at 10:40 AM, Tommaso Francese <
neutrinofrancese at gmail.com> wrote:

> Dear all,
>  as you suggested, i try to follow your tutorial for the Hubbard U
> coefficients determination, but i have some practical difficulties.
>
> Summarizing, i proceded as follow:
>
> step 1)?> i have done a simple SCF with very low coefficients for
> Hubbard_U1 and Hubbard_U2, enabling the wavefunction separate collection
> (wf_collect) ;
>

I don't think wf_collect is necessary. should not be harmful either


> step 2)?> i have performed some SCF, restarting from the charge file
> stored previously,  introducing some fluctuation values in Hubbard_alpha
> (?), is it correct?
>
>
right.


> the problem is at this point: do i need to rename every scf-file in which
> i performed a different perturbation?



yes, otherwise you overwrite them each time. or you can redirect them to
different (properly named) directories.



> How can i, in the next step, ?recall? the different perturbation that i
> performed previously?
>
>
what do you exactly mean by "recall"? do you have difficulties in
recognizing outputs corresponding to different alphas? then see the naming
problem at the previous point.


> At this point is obvious that i don?t know also how to calculate the
> response functions and so, obtaining the Hubbard U coefficient.
>
>
this is what the tutorial is for. were you able to follow the instructions
to the end? Besides the one from the Santa Barbar school there is also
another one from a nother school in 2012 at Penn State. Maybe that is
better?

best,

Matteo




> Can someone help me?
> Thanks a lot,
> Tommaso,
> Universit? C? Foscari of Venice
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://pwscf.org/mailman/listinfo/pw_forum
>
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Message: 6
Date: Fri, 16 May 2014 18:00:01 +0800
From: Pang Rui <pang.r at sustc.edu.cn>
Subject: Re: [Pw_forum] Hubbard U
To: PWSCF Forum <pw_forum at pwscf.org>
Message-ID: <808f3429f31a41da6936fe47b999f2c5 at 127.0.0.1>
Content-Type: text/plain; charset=UTF-8

Dear Tommaso:
I think maybe there are some misuderstanding. The following is what I do. 
1:calculate a scf and save all the output(the key is the *.save folder in
fact)
2:Bulid several folders, for example, 10.
3:Copy the scf file into the 10 folders
4:Put the perturbative input files which have different hubbard alpha into
the 10 folders and do the calculation. Of course, some additional input
must be added as Mr.Cococcioni suggested in the other mail of you. 
5:Grep "Tr" in every output files. The second one is the n0, the last one
is the n.Record the data of the one you take perturbation
6:Fitting two lines of n and n0(x) vs hubbard_alpha(y), the difference of
the slopes is the Hubbard U.
This is the process of calculating single U in a cell.
Hope this can help you.
On Fri, 16 May 2014 10:40:54 +0200, Tommaso Francese
<neutrinofrancese at gmail.com> wrote:
> Dear all,
>  as you suggested, i try to follow your tutorial for the Hubbard U
>  coefficients determination, but i have some practical difficulties.
> 
> Summarizing, i proceded as follow:
> 
> step 1)?> i have done a simple SCF with very low coefficients for
> Hubbard_U1 and Hubbard_U2, enabling the wavefunction separate collection
> (wf_collect) ;
> step 2)?> i have performed some SCF, restarting from the charge file
> stored previously,  introducing some fluctuation values in Hubbard_alpha
> (?), is it correct? 
> 
> the problem is at this point: do i need to rename every scf-file in
which
> i performed a different perturbation? How can i, in the next step,
?recall?
> the different perturbation that i performed previously? 
> 
> At this point is obvious that i don?t know also how to calculate the
> response functions and so, obtaining the Hubbard U coefficient.
> 
> Can someone help me? 
> Thanks a lot,
> Tommaso,
> Universit? C? Foscari of Venice
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://pwscf.org/mailman/listinfo/pw_forum


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